Which initial investigations should be performed to confirm a diagnosis of hypopituitarism?

Initial investigations to confirm a diagnosis of hypopituitarism include:

• Measurement of basal pituitary hormone levels, including adrenocorticotropic hormone (ACTH), growth hormone (GH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin to assess pituitary function.
• Serum cortisol measurement, preferably an 8 am to 9 am serum cortisol test, to evaluate adrenal axis function and exclude adrenal insufficiency.
• Thyroid function tests (TSH and free thyroid hormones) to assess for secondary hypothyroidism due to pituitary dysfunction.
• Gonadotrophin (LH and FSH) levels, especially in patients with irregular menstrual cycles or sexual dysfunction, to evaluate gonadal axis involvement.
• Additional dynamic endocrine testing may be required in secondary care to confirm deficiencies, but initial screening is based on basal hormone levels and clinical suspicion.

These investigations are particularly indicated in patients with symptoms consistent with hypopituitarism or those with risk factors such as previous head injury, pituitary or hypothalamic tumors, or radiotherapy to the cranial area ¹,²,³,⁴.